COMMUNITY FORUM

Removal of columns

I am in the process of refininshing my basement. I would like to remove one (preferably two) lally columns. The foundation measures 24' x 42' (exterior), all floor joists are 2x8's; main beam is 3) 2x8's spiked together; knee wall is stick built 2x4 construction; lally columns about 6'-11" apart (5 of them).

My plan is as follows: 1) Have head room to add 2) 16'- 2x12's to both sides of beam (6'-8" headroom under). 2) Add bearing wall from 15'-3" to next post (@ approx. 21' [CL] point along main beam). 3) According to tables I've read, span for 4) 2x12's (from memmory, don't have tables handy) is about 12'9".

My question(s), If I were to support gable end of beam by the foundation thickness (~10"),and leave existing beam in place, and bolt through all 7) 2x's [2 rows staggered, 3 1/2" apart, @ 16 o.c.) and attach together with 1/2" hardware, can I extend new beam to about a 15'-3" span and remove the two columns, (or only the first one) and still maintain the required structural support for the floor above (Split level home).

According to some old (1940/50's vintage) Audel books I've read, and doing some quick Pcs calculations found there, I should be able to. Don't really know for sure. Would like a little back-up.

If my idea is not valid as it stands, any other suggestions as to how you may have solved a similar situation?

Thanks in advance,

cadman

BobF

05:53AM | 04/22/99

You don't need to post in so many places.

Kansaz

10:24PM | 04/22/99

Problems like this really can't be solved with any degree of certainty without exact calculations i.e. no span tables. However, you seem to be on the right track and If you don't do the precise calculations to find the minimum cross-sectional area for your beam...try to err on the safe side. To sturdy a beam rarely hurts. I think you may be overdoing it a bit on the 1/2" bolts @ 16" o.c. You could probably just clamp the assembly well and run 3" deck screws staggered 16" o.c. All you really have to do is hold the assembly together. Too many holes will just make stress cracks more likely